4th EucheMs chemistry congress

Poster Session 1
s1017
chem. Listy 106, s587–s1425 (2012)
Poster session 1 - organic chemistry
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funCtionALizAtion of PoLyMer CoAted
MAGnetiC nAnoBeAdS By MiCrowAve
irrAdiAtion
C. M. eiChenSeer 1 , q.M. KAinz 1 , o. reiSer 1
1 University of Regensburg, Institute of Organic Chemistry,
Regensburg, Germany
Numerous studies demonstrate that heating by microwave
irradiation in sealed vessels can reduce reaction times
significantly. Additionally, compared to traditional heating higher
product yields are often obtained because of fewer side reactions.
The solvent employed plays a decisive role in the effectiveness
of the heating by absorbing the microwave irradiation. Many
nonpolar solvents, however, absorb little microwave energy. To
circumvent this problem strongly absorbing passive heating
elements (PHEs) can be added to the reaction mixture, e.g.
cylinders made out of silicon carbide. [1] We investigated here if
highly magnetic metal nanobeads can act as PHEs. The
nanoparticles (Fe/C or Co/C) used in these experiments combine
a metal core for rapid microwave absorption and magnetic
separation and a shell of carbon for higher stability under basic
and acidic conditions, while the high surface area and the good
dispersion in the reaction mixture are advantageous in the heat
distribution over massive PHEs. Surface functionalization was
achieved via radical polymerization leading to a high loading of
benzyl chloride moieties (> 3 mmol/g). [2] Starting from these
polymer coated nanobeads a recyclable magnetic Wang aldehyde
scavenger was prepared by substitution of the benzyl chloride
moieties with 4-hydroxybenzaldehyde under microwave
irradiation. Similarly, a magnetic borohydride resin was prepared
by heating with triethylamine in ethanol and subsequent exchange
of the chloride counterion with borohydride. Both substitution
reactions proceeded quantitative within minutes under microwave
irradiation while conventional heating led to incomplete
conversion despite considerably prolonged reaction times
(3 days). Building on these results, furan or maleimide moieties
could be immobilized as anchors for a thermally triggered and
reversible Diels Alder – Retro Diels Alder pathway for the
immobilization of fluorescent dyes or even catalysts.
references:
1. Kremsner, J. M.; Kappe, C. O. J. Org. Chem. 2006, 71,
4651-4658
2. Schätz et al. Chem. Eur. J. 2011, 17, 10566-10573
Keywords: Nanoparticles; Microwave irradiation;
4 th EucheMs chemistry congress
P - 0 3 1 2
SyntheSiS, AntioxidAnt And AntituMor
ACtivitieS of SoMe new PyrAzoLoPyridineS
under MiCrowAve irrAdiAtion And
ConventionAL heAtinG PArt ii
M. eL-BorAi 1 , h. rizK 1 , d. eL-BeLtAGy 2
1 Faculty of Science, Chemistry department, Tanta, Egypt
2 Faculty of Science, Chemistry department, Damanhour, Egypt
The reaction of DMF-DMA with 1-phenyl-3-(pyridin-3-yl)-
-1H-pyrazol-5-(4H)-one (1) gave the corresponding 4-
-(dimethylaminomethylene)-1-phenyl-3-(pyridin-3-yl)-1H-pyrazol-
-5(4H)-one (enaminone) (2). The chemical behavior of (2) with
active methylene reagents namely as β-ketonitriles, malononitrile,
cyanoacetamide, cyanothioacetamide and ethyl nicotinoyl acetate
was examined. Also, the reaction of (2) with some
3-substituted-5-amino-1H-pyrazoles was prepared to give
bis-pyrazolopyrimidine derivatives. All the prepared compounds
were carried out by conventional heating and microwave
irradiation technique to give the same products. The results of
both methods were compared including yield and time of
the reactions. The antioxidant activity of the prepared compounds
was studied. Also, some of the prepared compounds were tested
for antitumor activity against liver and breast cell lines.
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc